It looks like it was even signed, but not by a pun of the Nick show creators. The best I can read is "Akheri" or something to that degree. Starting with an "A".
(And if not, I'm going to save that name for later use)

I just noticed that it appears Michelangelo has been thrown through a glass ceiling too.

Looks like the first panel from the five panel spread in the original post. That's cool that all issues will connect to make the larger image. I wonder if the last issue will also contain some sort of removable five-panel fold out poster?

In a world of giant flying fish monsters, only one creature is strong enough to survive—Anemon! Will the Turtles be able to defeat him and bring him to testify at the Trial of Krang?
Variant cover by Kevin Eastman!
FC • 32 pages • $3.99

Huh, so it seems like the guys will be traveling to different parts of Dimension X in search of people to testify against Krang. Neat! This'll give us an opportunity to see different worlds and creatures, not to mention seeing what the artists are really capable of drawing.

Still, I'm wondering how it aligns with the Trial storyline. Before, after, or overlapping? And if it's overlapping, who leads the Trial storyline?
It would be interesting if it were Krang himself, but I doubt it.